yoda9999:<br />This increases space junk.<br /><br />Me:<br />This will be far less a problem for lunar missions. One reason, the stage that sends them on the way to the moon will push the CEV/LSAM combo to earth escape velocity (24,500 mph). When the propulsion stage separates, it goes into its own solar orbit or crashes into the moon for moon quake study if the TLI (Trans Lunar Injection) burn is done the same way Apollo was. The departure stage cannot return to Earth once escape velocity is achieved without a crapload of additional propellant.<br /><br />Like the Apollo LM. The LSAM is divided into two peices. An ascent stage and a descent stage. What you saw on the moon was the descent stage. This stage would sit with propellant tanks empty on the moon, the ascent stage carries the crew back to the CEV in lunar orbit. Once the crew transfers to the CEV, the LSAM ascent stage is jettisoned. And yes, a new descent and ascent stage would be part of each new LSAM mission and they are launched together on the Aries 5 while the next CEV goes up on the Aries 1.<br /><br />The problem with reuse of the stages is that once emptied, the stage is just dead weight being drug along which would of course, severely limit the performance of remaining fueled stages or vehicles. Example. The departure stage if kept after the TLI burn, will impose a severe drag penalty on the CEV/LSAM stack and so on.<br /><br />If you remember Delta Clipper, the subscale Single Stage To Orbit (SSTO) vehicle tested in the early 1990s, a slightly larger version of this type of vehicle could serve in place of an LSAM and be totally reusable theoretically, but the propellant required would limit payload to the lunar surface and especially any payload launched from the lunar surface.<br /><br />In addition, the development of SSTO technology is still the stuff of future spaceflight. More expensive to do than just doing the modernized Apollo.<br /><br />NASA never builds something for the sake of being new and fancy <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>